Proteoglycan is one of the major biological macromolecules for forming the substrate of the extracellular matrix of connective tissue, as with collagen, etc. Proteoglycan was hitherto obtained by being extracted and isolated from mammal cartilage (in particular, bovine cartilage). However, since the onset of bovine spongiform encephalopathy (BSE) was reported, there has been a need for an alternative source of proteoglycan, and a production method therefor.
As an alternative source for proteoglycan, aquatic animal tissue is attracting attention. Therefore, there have been attempts to extract proteoglycan from cartilage of aquatic animals, such as whales or sharks. However, due to harvest restrictions placed on these aquatic animals, it has been difficult to produce a large amount of proteoglycan. Moreover, the extraction and isolation of proteoglycan is complicated, and the solvents used for extraction have certain levels of toxicity. Therefore, the usage of proteoglycan products is limited, and they were difficulties in using them as materials of foodstuff or cosmetics.
Under such circumstances, there has been active research into various proteoglycan production methods. For example, Patent Document 1 discloses a method for purifying proteoglycan. In this method, salmon nasal cartilage is pulverized and defatted to obtain defatted dry powder, which is then subjected to extraction using a solvent. The obtained coarse extract is isolated and purified, followed by dialysis. However, this method uses an organic solvent having a certain level of toxicity, such as chloroform or methanol. Another problem of this method is that a fishy smell remains on the resulting proteoglycan.
Patent Document 2 discloses a method for purifying proteoglycan from salmon nasal cartilage using an acetic acid as an extraction solvent. Further, Patent Document 3 suggests a capability to proliferate fibroblasts, and an effect of promoting hyaluronic acid synthesis of the proteoglycan produced by the method of Patent Document 2.
As explained above, there is still ongoing research into the production, usage, and effects of proteoglycan.